Anusorn Kongkanand

Performance of Nano Structured Thin Film (NSTF) Electrodes under Partially-Humidified Conditions

3M’s Nano Structured Thin Film (NSTF) electrode, being a core-shell catalyst, offers a novel mean to enhance the performance and lower Pt cost in a polymer electrolyte fuel cell (PEFC). In the present work, fuel cell performance of NSTF is reported and the underlying physics dictating NSTF behavior is probed. It was found that NSTF with 0.15 mgPt/cm 2 Pt loading shows comparable performance to that of a conventional Pt/C electrode with 0.4 mgPt/cm 2 loading in a highly humidified condition at 80 C. However, the NSTF performs poorly under dry conditions. A single-phase model was developed to elucidate the underlying phenomenon governing NSTF performance under partially-humidified conditions. NSTF proton conductivity as a function of relative humidity (RH) was determined and the model predictions were compared against a range of experimental data. Detailed results suggest that poor NSTF performance under dry operation is due to low proton conductivity over Pt surface, which reduces catalyst utilization. The importance of water management is highlighted to improve NSTF performance. VC 2011 The Electrochemical Society. [DOI: 10.1149/1.3590748] All rights reserved.

Load Transients of Nanostructured Thin Film Electrodes in Polymer Electrolyte Fuel Cells

Transient responses of conventional carbon-supported Pt nanoparticle (Pt/C) and 3Ms nano structured thin film (NSTF) oxygen reduction electrodes are reported. The ultrathin 0.3 μm thick NSTF electrode exhibits less-than-zero voltage, i.e. a failed up-transient, when current is increased instantaneously from 0.02 to 1.0 A/cm 2 at 80°C and the channel RH is greater than 80%. In contrast, under the same conditions, a 10 μm thick Pt/C electrode exhibits robust transient response. A transient model, coupled with experiments, is deployed to delineate the water transport dynamics and ensuing voltage response. It is found that thin electrodes, due to their low water storage capacities, flood with liquid water rendering negative cell voltages during transients. Effects of operating conditions and material properties such as membrane and electrode thickness on the transient response are investigated.

Electrode Structure Effects on Current Up-Transient Operation in Polymer Electrolyte Fuel Cells

Transient responses of conventional carbon-supported Pt nanoparticle (Pt/C) and 3Ms nanostructured thin film (NSTF) oxygen reduction electrodes are reported. The ultrathin 0.3 μm thick NSTF electrode exhibits less-than-zero voltage, i.e. a failed up-transient, when current is increased instantaneously from 0.02 A/cm2 to 1.0 A/cm2 at 80°C and the channel RH is greater than 80%. In contrast, under the same conditions, a 10 μm thick Pt/C electrode exhibits robust transient response. A transient model, coupled with experiments, is deployed to delineate the water transport dynamics and ensuing voltage response. It is found that thin electrodes, due to their low water buffer capacities, flood with liquid water rendering negative cell voltages during transients. Effects of operating conditions and electrode thickness on the transient response are investigated.